212 A MANUAL OF THE BIRDS OF AUSTRALIA. 
Generally the Grebes have been placed distant from the Rails, but there can 
be little doubt that this is their correct place. The palate of the skull is 
schizognathous and the nasals holorhinal, and there are no basipterygoid processes. 
It has been written by an osteologist that it would be difficult to find differences in 
the skulls of the Grebes and Rails. The cervical vertebrae are twenty-one in number, 
the sternum is one notched and there is no anterior spine, and the procoracoid is 
absent. There is only one carotid and the digestive system does not appear to 
have been particularly studied, but may be similar to the Ralline style. The leg 
muscle formula is BX—, whichis instructive. The oil gland is tufted, the aftershaft 
present and the wing aquincubital. The pterylosis has not been comparatively 
determined, and the swimming downy nestling is of a peculiar striped coloration. 
While fossils are on record as suggested relations of this group, as this has continually 
been confused with the phylogenetically distinct group of Divers (= Colymbiformes, 
a suborder of the Lari or Limicole), it is difficult to consider such at present. Thus 
the Hesperornithes from the Cretaceous of North America have been regarded as 
showing ancestral features of both Grebes and Divers, but such conclusions do not 
seem to have been based on sound premises, and most of the resemblances noted 
are simply due to similar environmental stresses. 
Famiry PODICIPIDA:. 
The limits are those of the order, and some workers are diffident in accepting 
many genera, as the ordinal form is omnipresent. However, both osteologists and 
anatomists have recorded, according to their views, important items for separation, 
so that distinct genera must be accepted. Thus the syrinx in Podiceps and Polio- 
cephalus is of different form, while the skull shows numerous differences also. It 
must be noted that the swimming habits of the Grebes have developed a strong tibial 
crest ; this is the most marked feature for the association of this group with the 
Divers, but it is so purely an adaptive feature that it is difficult to understand why 
much stress was laid upon it with regard to phylogenetic relationship. 
Genus PODICEPS. 
Podiceps Latham, Gen. Synops. Suppl., Vol. I., p. 294, (pref. May Ist) 1787. Type (by 
subsequent designation, Gray, p. 76, 1840): Colymbus cristatus Linné. 
Colymbus Mliger, Prodr. Mamm. et Av., p. 281, (pref. April) 1811. Type (by subsequent 
designation, Ogilvie-Grant, Cat. Birds Brit. Mus., Vol. XXVI., p. 502, 1898): Colymbus 
cristatus Linné. 
Not Linné, Syst. Nat., 10th ed., p. 135, Jan. Ist, 1758. 
Lophaithyia Kaup, Skizz. Entwick.-Gesch. Nat. Syst., p. 72, (pref. April) 1829. Type (by 
monotypy): C. cristatus Linné. 
Largest Grebes, with long straight bills, short rounded wings, rudimentary 
tail and peculiar, flattened tarsi, and largely lobed toes with broad, flattened claws. 
Bill long, straight, and pointed, sometimes slightly curved at the tip; nostrils 
pervious, and placed at the base of the upper mandible. Wings very short and 
rounded, the feathers narrow and pointed, the first longest, the secondaries usually 
as long as the primaries. Tail rudimentary, consisting of a tuft of downy feathers, 
no rectrices being distinguishable. Tarsus shorter than the middle toe and claw, 
compressed so as to form a ridge anteriorly and posteriorly, where it is serrated. 
The toes are flattened and surrounded by large lobes of skin, only connected at the 
base, not contracted at the joints. The claws are also flattened, forming part of 
the lobe ; the fourth toe is the longest, the hallux is small and also provided, like 
the others, with a lateral lobe. The anterior ridge is regularly scutellate, and the 
